code: def _compute_bu_gnmax(q, sigma, num_classes):
      return min(
          1,
          (num_classes - 1)
          / 2
          * scipy.special.erfc(
              -1 / sigma
              + scipy.special.erfcinv(2 * q / (num_classes - 1))
          ),
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import math
  from absl import app
  import numpy
  import scipy
  import sympy
  import core
label_desc: Use image node_id 8 for calling a global function with example usage: _compute_bu_gnmax(q, sigma, num_classes) and returns: min